Dyslexia is a major problem of human development. It is a disorder manifest by difficulty in learning to read despite conventional instruction, adequate intelligence and socio-cultural opportunities, and arises from fundamental cognitive disabilities.
Dyslexia is four to five times commoner in boys than girls, commoner in children with atopic eczema and asthma than those without, and also commoner in offenders than the law abiding. It is associated with a loss of normal brain asymmetry which is demonstrable using modern brain scanning methods and also on functional tests. It is recognised to be a disorder with an organic basis.